...numquam enim in praestantibus in re publica gubernanda viris laudata est in una sententia perpetua permansio....and
...for persistence in a single permanent opinion among men [sic] active in the governance of the republic has never been praised....
ad Familiares 1.9.21
nemo doctus umquam ... mutationem consili inconstantiam dixit esse.
No educated person has ever said that a change of mind was inconsistency.
ad Atticum 16.7.3
Of course, Cicero ended up with his head and hands mounted on the Rostra, so caveat lector.